Portable mortar



Nov. 28, 1944- M. M. JOHNSON, JR

PORTABLE MORTAR Filed Oct. 20, 1943 Patented Nov. 28, 1944 PORTABLEMORTAR Melvin M. Johnson, Jr., Brookline, Mass, assignor to Melvin M.Johnson, Melvin M. Johnson, Jr., and Edward E. Rice, as trustees of theJohnson Patent Trust, Boston, Mass.

Application October 20, 1943, Serial to. 506,998

Claims.

In modern warfare an effective defense against tanks and other armoredunits is a problem, particularly where portability in difficult terrainis involved. For the infantry an offensive weapon capable of destroyinpill-boxes, gun emplacements, and nests is also essential. Objects ofthe present invention are to provide a gun which has sufficientdestructive power for the aforesaid purposes, which is suflicientlylight to be carried, which has sufliciently low'i'ecoiLto be fired fromthe shoulder, which fires standard ammunition, which is simple andeconomical in construction, whichcan be assembled and disassembled withfacility, which is reliable and durable in use and which is generallysuperior to portable guns heretofore produced for similar purposes.

The subject-matter of the present invention is like a mortar in that ituses standard mortar ammunition and is loaded by inserting theammunition into th barrel through the muzzle. According to the presentinvention the mortar has a tubular casing and a barrel slidable back andforth in the casing throughout a considerable distance, preferably adistance at least approximately as long as the ammunition used, together with a spring interposed between the casing and the barrelyieldingly to urge the barrel toward its advanced position, a scar tohold the barrel in retracted position against the action of theaforesaid spring, a firing pin carried by the rear end of the barrel,and means movabl relatively to the barrel for stopping ammunitionslightly in the rear of the aforesaid advanced position as it is loadedthrough the muzzle so that, when the sear is retracted to release thebarrel, the ammunition is not fired until the barrel approaches theaforesaid advanced position with sufficiently high momentum largely tocounteract the recoil of the gun, whereby it is possible to fire fromthe shoulder with ammunition more powerful than it has been possible touse heretofore in shoulder guns. For shoulder operation the gun ispreferably provided with a shoulder'piece and at least one hand gripunder the aforesaid casing, and for operation from prone position it mayalso be provided with a bipod mount.

In the preferred embodiment the outside diameter of the barrel is lessthan the inside diameter of the casing, the rear end of the barrel beingclosed by a head which has a sliding fit in th casing and the casinghaving at its forward end a bearing in which the barrel has a slidingfit. The aforesaid spring is preferably a coil spring interposed betweenthe casing and barrel around the forward end of the barrel, the forwardend of the spring abutting a ring detachably mounted on the forward endof the barrel and the rear end of the spring abutting the aforesaidbearing. The preferred means for stopping the ammunition in forwardposition as it is loaded in the barrel comprises a rod sliding throughthe rear end of the barrel with its rear end engaging a stop on thecasing and its forward end projecting into the barrel in the path of theammunition. The rod may have a shoulder on its forward end engageablewith the barrel as the barrel approaches its advanced position so thatthe rod travels with the barrel throughout the forward end of the barrelstroke, in which case a spring is preferably interposed between the rodand the barrel yieldingly to urge the rod rearwardly against theaforesaid stop.

For the purpose of illustration a. typical embodiment of the inventionis shown in the accompanying drawing in which Fig. 1 is a top plan viewshowing the barrel partially extended as at the moment of firing;

Fig. 2 is a vertical longitudinal section showing the barrel latched inretracted position ready to fire;

Fig. 3 is a section on line 33 of Fig. 2;

Fig. 4 is a section on line 4-4 of Fig. 2; and

Fig. 5 is a rearelevation.

The particular embodiment of the invention chosen for the purpose ofillustration comprises a casing formed in two cylindrical parts, a mainrear portion l and an extension 2 threaded into the forward end of thebody portion. Threaded over the rear end of the casing is a cap 5 andsecured to the cap is a shoulder piece It. The barrel comprises acylindrical tube 3 having a diameter less than that of the casing and ahead I threaded over the rear end of the tube, the head having a slidingfit in the casing I. The head 4 carries an integral firing pin 6 and adetachable actuator 1 which projects outwardly through a slot 8 in thecasing. Mounted in the forward end of the casing l is a bearing ring 9in which the barrel 3 has a sliding fit. Detachably mounted on theforward end of the barrel 3 is a split ring H which is clamped on thebarrel by means of a screw l2. Interposed between this ring and thebearing ring 9 is a coil spring I3 which yieldingly urges the barreltoward its advanced position. The aforesaid stop comprises a rod I 4slidable back and forth in the head 4 and having heads I 6 and H on itsforward and rearward ends, a coil spring l8 surroundin the rod betweenthe heads 4 and I1 yieldingly to urge the rod rearwardly against therear end of the casing I.

While the gun preferably has; semi-automatic firing mechanism so that itis self-cocking even though the trigger is not released before thebarrel recoils, for the purpose of simplifying the illustration Fig. 2merely shows a sear 2| and a trigger 22 pivotally supported at 23 and 24in a frame 28 which has a dovetail connection with flanges 21 fast tothe bottom of easing I. Fast to the bottom of the subframe 26 is a hand.grip 28 having a recess 29 at its forward side to receive the dependingportion of the trigger,the trigger being operable by several fingersinstead of a single finger. The rear end of the sear extends into agroove in the head 4 to hold the barrel in the cocked position shown inFig. 2.

While any suitable mortar ammunition may be employed a typical kind isshown at Min Figs. 2 and 3, this kind comprising a detonator 32 attheforward end to explode the shell when it hits the target and at therearward end a cap 33 engageable by the firing pin 6 when the gun isfired. The rear end of the shell is also provided with fins 34, the headof the rod It being larger than the openings between the fins so that inloading the gun through the muzzle the shell is always stopped in theposition shown in Fig. 2.

In operation the gun is first cocked by retracting the barrel intoengagement with the sear as shown in Fig. 2, the barrel being retractedeither by pulling on the actuator I or by pushing the forward end of thebarrel against an abutment or both. After the gun has been cooked theammu nition is inserted through the muzzle to the position shown in Fig.2. Upon release of the barrel by pressing the trigger the barrel springsforward in response to the spring l3. When the firing pin engages theammunition the cartridge is fired from the gun as in an ordinary mortar.Thus at the instant of firing the barrel is moving forwardly so thatbefore recoil the forward momentum must be absorbed. In this way therecoil is greatly reduced, the degree of reduction depending upon theweight of the'barrel and the strength of the spring l3. As the barrelsprings forward the inertia of the shell holds it substantially in theposition shown in Fig. 2 until it is fired; At the moment of firing thebarrel has advanced to the position shown in Fig. 1. While the barrelcontinues forwardly a short distance 'until its momentum is overcome bythe force of loaded. The rod ll remains stationary until'the precision.For this purpose suitable sights may be provided on the casing.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modificationsand equivalents which fall within the scope of the appended claims.

rel for. stopping ammunition slightly in the rear of said advancedposition, whereby when said 'sear is retracted the ammunition is notfired until the barrel approaches said advanced position with highmomentum which largely counteracts the recoil. j V

2. A mortar comprising a tubular casing, a

shoulder piece at the rear endof the casing, a hand grip under thecasing, a barrel slidable.

back and forth in the casing, between an ad- .vanced position and aretracted position,

throughout a distance at leastapproximately as long as the ammunitionused therein, a spring interposed between the casing and barrelyieldingly to urge'the barrel toward said advanced position, a sear tohold the barrel in said retracted position against the action of saidspring, a firing pin carried by the rear end of the barrel, and meansmovable relatively to the barrel for stopping ammunition slightly in therear of said advanced position, whereby when said sear is retracted theammunitionis not fired until the barrel approaches said advancedposition with high'momentum which largely counteracts the recoil.

3. Aniortar comprising a tubular casing, a barrel slidable back andforth in the casing, between an advanced position and a retractedposition, throughout a distance at least approximately as long as theammunition used therein, the outside diameter of the barrel being lessthan the inside diameter'of the casing, the rear end of the barrel beingclosed by a head which has a sliding fit in the casing, a bearing on theforward endof the casing in which the barrel has a sliding fit, a springinterposed between the casing and barrel yieldingly to urge the barreltoward said advanced position, a sear to hold the barrel in saidretracted position against the action of said spring, a firing pincarried. by the rear end 'of' the barrel, and means movable relativelyto the barrel for stopping ammunition slightly in the rear of saidadvanced position, whereby when said sear is retracted the ammunitionisnot fired until the barrel approaches'said advanced position with highmomentum which largely counteracts the recoil; I

4. A mortar comprising a tubular casing, a

- barrel slidable back and forth in the casing, be-

tween an advanced position and a retracted position, throughout adistance at least approximately as long as the ammunition used therein,a

coil spring 'interposed between the casing and barrel around the forwardend of the barrel yieldingly to urge the barrel toward said advancedposition, a sear to hold the barrel in said retracted position/ againstthe action of said spring, a firing pin carried by the rear end of thebarrel, and means movable relatively to the barrel for stoppingammunition slightly in the rear of said advanced position, whereby whenaseaevo said sear is retracted the ammunition is not fired until thebarrel approaches said advanced position with high momentum whichlargely counteracts the recoil.

5. A mortar comprising a tubular casing. a barrel slidable back andforth in the casing, between an advanced position and a retractedposition, throughout a distance at least approximately as long as theammunition used therein, a coil spring interposed between the casing andbarrel around the forward end of the barrel yieldingly to urge thebarrel toward said advanced position, a ring detachably mounted on theforward end of the barrel to abut the forward end of the spring, a searto hold the barrel in said retracted position against the action of saidspring, a firing pin carried by the rear end of the barrel, and meansmovable relatively to the barrel for stopping ammunition slightly in therear of said advanced position, whereby when said sear is retracted theammunition is not fired until the barrel approaches said advancedposition with high momentum which largely counteracts the recoil.

6. A mortar comprising a tubular casing, a barrel slidable'back andforth in the casing, between an advanced position and a retractedposition, throughout a distance at least approximately as long as theammunition used therein, the outside diameter of the barrel being lessthan the inside diameter of the casing, the rear end of the barrel beingclosed by a head which has a sliding fit in the casing, a bearing on theforward end of the casing in which the barrel has a sliding fit, a ringdetachably mounted on the forward end of the barrel, a coil springinterposed between said bearing and ring yieldingly to urge the barreltoward said advanced position, a sear to hold the barrel in saidretracted position against the action of said spring, a firing pincarried by the rear end of the barrel, and means movable relatively tothe barrel for stopping ammunition slightly in the rear of said advancedposition, whereby when said sear is retracted the ammunition is notfired until the barrel approaches said advanced position with highmomentum which largely counteracts the 45 recoil.

'7. A mortar comprising a tubular casing, a barrel slidable back andforth in the casing, between an advanced position and a retractedposition, throughout a distance at least approximately as long as theammunition used therein, a coil spring interposed between the casing andbarrel in an annular space between the casing and barrel yieldingly tourge the barrel toward said advanced position, a sear to hold the barrelin said retracted position against the action of said spring, a firingpin carried by the rear end of the barrel, and means movable relativelyto the barrel for stopping ammunition slightly in the rear of saidadvanced position, whereby when said sear is retracted the ammunition isnot fired until the barrel approaches said advanced position with'highmomentum which largely counteracts the recoil.

8. A mortar comprising a tubular casing, a barrel slidable back andforth in the casing, between an advanced position and a retractedposition, throughout a. distance at least approximately as long as theammunition used therein, a coil spring interposed between the casing andbarrel in an annular space between the casing and barrel yieldingly tourge the barrel toward said advanced position, the forward portion ofthe casing surrounding said spring being detaohably mounted on the rearportion of the casing, a sear to hold the barrel in said retractedposition against the action of said spring, a firing pin carried by therear end of the barrel, andmeans movable relatively to the barrel forstopping ammunition slightly in the rear 01' said advanced position,whereby when said sear is retracted the ammumtion is not fired until thebarrel approaches said advanced position with high momentum whichlargely counteracts the recoil.

9. A mortar comprising a tubular casing, a barrel slidable back andforth in the casing, between an advanced position and a retractedposition, throughout a distance at least approximately as long as theammunition used therein, a spring interposed between the casing andbarrel yieldingly to urge the barrel toward said advanced position, asear to hold the barrel in said retracted position against the action ofsaid spring, a firing pin carried by the rear end of the barrel and arod sliding through the rear end of the barrel with its rear endengaging a stop on said casing and its forward end projecting into thebarrel to stop ammunition slightly in the rear of the closed end of thebarrel when in said advanced position. whereby when said sear isretracted the ammunition is not fired until the barrel approaches saidadvanced position with high momentum which largely counteracts therecoil.

10. A mortar comprising a tubularcasing, a barrel slidable back andforth in the casing, between an advanced position and a retractedposition, throughout a distance at least approximately as long as theammunition used therein. a spring interposed between the casing andbarrel yieldingly to urge the barrel toward said advanced position, asear to hold the barrel in said retracted position against the action ofsaid spring, a firing pin carried by the rear end of the 0 barrel, a rodsliding through the rear end of the barrel with its rear end engaging astop on said casing and its forward end projecting into the barrel tostop ammunition slightly in the rear of the closed end of the barrelwhen in said advanced position, a shoulder on the forward end of the rodengageable with the barrel as the barrel approaches said advancedposition so that the rod travels with the barrel throughout the forwardend of the barrel stroke, and a. spring interposed between the rod andbarrel yleldingly to urge the rod rearwardly against said stop.

MELVIN M. JOHNSON, JR.

